ALS Mutants of Human Superoxide Dismutase Form Fibrous Aggregates Via Framework Destabilization

DiDonato, Michael; Craig, Lisa; Huff, Mary E.; Thayer, Maria M.; Cardoso, Renato; Kassmann, C.J.; Lo, Terence P.; Bruns, C.K.; Powers, Evan T.; Kelly, Jeffery W.; Getzoff, Elizabeth D.; Tainer, John A.

doi:10.1016/s0022-2836(03)00889-1

Cited by 182 publications

(194 citation statements)

References 71 publications

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“…Based on these results, we predicted that changes in pH that lead to titration of saltbridge residues should destabilize SOD1 and increase the population of folding intermediates. Recent experimental studies [40] and our observations of the pH-dependent destabilization of SOD1 [41] confirm this prediction.…”

Section: Sh3-domain Swappingsupporting

confidence: 84%

Simple but predictive protein models

Ding

Dokholyan

2005

Trends in Biotechnology

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Section: Sh3-domain Swappingsupporting

confidence: 84%

Simple but predictive protein models

Ding

Dokholyan

2005

Trends in Biotechnology

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“…A few of the isolated ALS-mutant SOD1 proteins have been induced to oligomerize in vitro to form amyloid-like aggregates, but the conditions used in each case were far from physiological, i.e., either very low pH (13) or extensive metalcatalyzed oxidation (14), suggesting that oligomerization occurred only if the SOD1 protein was substantially damaged or unfolded.…”

mentioning

confidence: 99%

Metal-free superoxide dismutase forms soluble oligomers under physiological conditions: A possible general mechanism for familial ALS

Banci

Bertini

Durazo³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

225

262

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Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder selectively affecting motor neurons; 90% of the total cases are sporadic, but 2% are associated with mutations in the gene coding for the antioxidant enzyme copper-zinc superoxide dismutase (SOD1). The causes of motor neuron death in ALS are poorly understood in general, but for SOD1-linked familial ALS, aberrant oligomerization of SOD1 mutant proteins has been strongly implicated. In this work, we show that wild-type human SOD1, when lacking both its metal ions, forms large, stable, soluble protein oligomers with an average molecular mass of Ϸ650 kDa under physiological conditions, i.e., 37°C, pH 7.0, and 100 M protein concentration. It further is shown here that intermolecular disulfide bonds are formed during oligomerization and that Cys-6 and Cys-111 are implicated in this bonding. The formation of the soluble oligomers was monitored by their ability to enhance the fluorescence of thioflavin T, a benzothiazole dye that increases in fluorescence intensity upon binding to amyloid fibers, and by disruption of this binding upon addition of the chaotropic agent guanidine hydrochloride. Our results suggest a general, unifying picture of SOD1 aggregation that could operate when wild-type or mutant SOD1 proteins lack their metal ions. Although we cannot exclude other mechanisms in SOD1-linked familial ALS, the one proposed here has the strength of explaining how a large and diverse set of SOD1 mutant proteins all could lead to disease through the same mechanism.amyloid ͉ neurodegeneration ͉ protein aggregation ͉ amyotrophic lateral sclerosis ͉ protein misfolding P rotein oligomerization, aggregation, and formation of insoluble amyloid deposits commonly are observed in neurodegenerative diseases, but the factors initiating and modulating the abnormal protein-protein interactions that lead to oligomerization remain elusive (1, 2). Metal ions frequently have been implicated in these phenomena, but how exactly they are involved remains unclear (3). Over 114 different variants of human copper-zinc superoxide dismutase (Cu 2 Zn 2 SOD1) have been linked to the neurodegenerative disease familial ALS (FALS) by a gain-of-function mechanism (4-6). Although the exact cellular sites and mechanisms of toxicity are unknown, aberrant SOD1 protein oligomerization has been strongly implicated in disease causation (7,8). Several recent publications have presented compelling evidence that abnormal disulfide cross-linking of ALS-mutant SOD1 plays a role in this oligomerization, and disulfide-linked SOD1 multimers have been detected in neural tissues of SOD1-ALS transgenic mice that are presumed to be components of higher-molecular-weight species or intermediates in their formation (7, 9-11).Wild-type (WT) human SOD1 is an exceptionally stable protein in its holo form and, although some of the ALS-mutant SOD1 proteins are severely destabilized by their mutations, others largely retain the stability of WT SOD1 (4). In the fully demetallated (apo) states, some ...

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“…Yet, it is not entirely clear how the many different Cu,Zn SOD single-site mutations, which are widely dispersed throughout the protein sequence, can give rise to the same FALS pathology. Some clarification was provided by combined structural, biochemical and biophysical characterizations of two FALS mutant SOD proteins (DiDonato et al, 2003). These two FALS proteins represent the two major structural classes of SOD mutations.…”

Section: Ros and Copperzinc Superoxide Dismutasementioning

confidence: 99%

“…To separate possible secondary destabilization and aggregative events due to oxidation of the free cysteine residues (C6 and C111) from changes caused directly by the H43R and A4V mutations, the mutations were examined in the context of the C6A/C111S HSOD (HSOD-AS) parent, which retains the wild-type fold and activity (McRee et al, 1990,Hallewell et al, 1991. These two mutants retain nearly wild-type structures, but an overall architectural destabilization of these proteins propagates from the point mutations, to promote the formation of fibril-like aggregates (DiDonato et al, 2003). The cysteine-independent aggregation of FALS mutants is enhanced by factors of 7-80 times, compared to the parent HSOD-AS.…”

Section: Ros and Copperzinc Superoxide Dismutasementioning

confidence: 99%

“…Visualization of these aggregates by electron microscopy and atomic force microscopy revealed that they resemble those found in post-mortem studies of FALS patients, and bind dyes that detect amyloid-like structure. Thus, the structural biochemistry data provides evidence for a molecular mechanism for initiating FALS toxicity, whereby framework destabilization and loss of dimer assembly specifically promote fibril formation, with consequent implications for mitochondrial damage and motor neuron cytotoxicity (DiDonato et al, 2003).…”

Section: Ros and Copperzinc Superoxide Dismutasementioning

confidence: 99%

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Developing master keys to brain pathology, cancer and aging from the structural biology of proteins controlling reactive oxygen species and DNA repair

2007

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This review is focused on proteins with key roles in pathways controlling either reactive oxygen species or DNA damage responses, both of which are essential for preserving the nervous system. An imbalance of reactive oxygen species or inappropriate DNA damage response likely causes mutational or cytotoxic outcomes, which may lead to cancer and/or aging phenotypes. Moreover, individuals with hereditary disorders in proteins of these cellular pathways have significant neurological abnormalities. Mutations in a superoxide dismutase, which removes oxygen free radicals, may cause the neurodegenerative disease amyotrophic lateral sclerosis. Additionally, DNA repair disorders that affect the brain to varying extents include ataxia-telangiectasia-like disorder, Cockayne syndrome or Werner syndrome. Here, we highlight recent advances gained through structural biochemistry studies on enzymes linked to these disorders and other related enzymes acting within the same cellular pathways. We describe the current understanding of how these vital proteins coordinate chemical steps and integrate cellular signaling and response events. Significantly, these structural studies may provide a set of master keys to developing a unified understanding of the survival mechanisms utilized after insults by reactive oxygen species and genotoxic agents, and also provide a basis for developing an informed intervention in brain tumor and neurodegenerative disease progression.

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ALS Mutants of Human Superoxide Dismutase Form Fibrous Aggregates Via Framework Destabilization

Cited by 182 publications

References 71 publications

Simple but predictive protein models

Simple but predictive protein models

Metal-free superoxide dismutase forms soluble oligomers under physiological conditions: A possible general mechanism for familial ALS

Developing master keys to brain pathology, cancer and aging from the structural biology of proteins controlling reactive oxygen species and DNA repair

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